Mag Tactical Systems Lightweight AR-15 Lowers

I posted recently about a new polymer AR-15 80% lower from Polymer80, well during another one of my AR lower shopping sprees I stumbled upon another lightweight AR-15 lower from Mag Tech Systems. Their Generation 4 Mag Tactical Systems AR-15 lower is 35% lighter than aluminum lowers on the market at just 5.875 ounces. Mag Tactical System constructs them out of a proprietary magnesium alloy and also uses a proprietary coating process to protect their lowers from corrosion. It features an integral trigger guard with room for winter gloves, a reinforced front pivot pin, reinforced trigger and hammer pin axis points and also includes extended trigger and hammer pins. They’re available in both black and flat dark earth and retail for $250, they’re available at Brownells at $169.99 however. Sure they’re a bit pricey compared to other lowers on the market, but if you’re looking to shave off as much weight as possible for your AR build and are hesitant to go the polymer route, the Mag Tech Systems lower might be the ticket.



Ray I.

Long time gun enthusiast, archery noob, Mazda fan, Sci-Fi nerd, Whiskey drinker, online marketer and blogger. My daily firearms musings can be found over at my gun blog and Instagram.

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  • Mike F Di

    dont know if I trust a magnesium ANYTHING…fire hazard and sheer corrosion issues.
    and it is a bit pricey once the craziness dies off.. good idea…wrong material.
    I understand the need to have them made via casting and pricing involved for materials and methods. just really they should’ve gone with TITANIUM, non reactive and way way stronger. now that is a Element (Titanium) I like on the periodic tables for gun parts..
    until we get a batch of the stuff Wolverines claws are made of….Titanium is it!!!

    • Nick

      It says magnesium alloy, as in it’s mixed with other metals. Airplanes have a lot of parts made of magnesium alloys, they’re very strong, light and not very reactive.

      • noob

        Also mag wheels on cars. You can get alloys that are quite safe for the kind of duty that the lower will experience.

        Having said that a metallic Ti lower would be fun… if only you can show it to your friends and boast about *how much it cost* 😛

        • Raven

          There’s been at least one incident in which magnesium car parts caused a whole lot of trouble in a crash. The 1955 LeMans disaster was exacerbated by the ruptured fuel tank on the car igniting the magnesium alloy (called Elektron, also used in incendiary bombs) body. And of course it’s impossible to extinguish burning magnesium with water.

          Titanium isn’t as incendiary, but it is very hard to machine and is less stiff than aluminum alloy or carbon fibre. It can’t be cast either unless you invest in vacuum chamber or inert-gas casting area.

          • Laserbait

            I would think that things have improved somewhat in the 65 years after that incident.

          • Ian

            Elemental properties don’t just “improve”.

          • JumpIf NotZero

            I don’t know where these myths about Ti come from. It is heavier than Ti, but you are incorrect to say its less “stiff” than aluminum.

            For all practical concerns, Ti is a good stainless at half the weight. End of story. No harder to machine than a good stainless, very similar strength and corrosion. That is assuming grade5 Ti which is the common good stuff. Grade2 and pure Ti is pretty just identical to aluminum for strength, but not corrosion.

          • dragon5126

            WRONG titanium toolings are used to machine stainless, carbide to machine titanium… and how can Ti be heavier than Ti???

          • dragon5126

            Raven recheck your race history… it wasn’t a fire, it was a crash that sent the car right into the stands… it’s called the 1955 Le Mans Massacre…

    • @FarmTeamInfidel

      Aluminum is lighter than titanium and the only time I’ve seen magnesium catch fire is if it’s shavings. I was shortening a titanium drive shaft once on a chop saw and sparks landed on a drill press where I had magnesium shavings laying on a piece of wood and they ignited. I’ve collected shaving before and lit them in a can, the stuff burns extremely hot – but I don’t believe mag in a solid form will ignite.

      • le happy merchant

        Why wouldnt solid magnesium ignite? Google around for pics of a burning NeXT (computer) cube.

        • @FarmTeamInfidel

          “This is a good demonstration ( of how the physical form of a substance can have a huge effect on its properties. As a powder magnesium explodes, as a thin strip you can light it with a match, as a bulk solid you may never get the stupid thing lit. Same with corn starch: As a bulk solid you bake with it in a gas oven, as a fine powder it has been known to explode set of by no more than a spark of static electricity (this happens in grain elevators, which do not survive).”

          • dragon5126

            corn starch is not explosive neither is grain powder but grain powder is very flammable and that is what burns in grain silos and any flame front when confined creates pressure. this is how smokeless works as opposed to black powder which IS explosive and must be compressed or you risk damage to the barrel… half the information leads to false conclusions. Starch will not burn without a carbon catalyst, just like sugar, it will only scorch. and powdered magnesium does not explode if it did we would all be dead. powdered magnesium and resin are what sparklers are made out of…

          • dragon5126

            only a moron would down vote the laws of physics…

    • bob

      Titanium is heavier than aluminum

    • dragon5126

      Mike go buy a Chinese made magnesium fire starter… they don’t burn, LOL seriously there is even a vid on youtube about it. the guy took a torch to the magnesium alloy shavings and they would not ignite. Magnesium alloy does not corrode either. And titanium would not work it would literally cut the pivot pins. If you look at what they use titanium for in firearms it is very limited because it is brittle and would shatter were it used as a receiver…

  • noob

    interesting. they even cut out the less stressed parts around where the pistol grip attaches.

    I would like to see what a rifle with this lower and a bushmaster Carbon15 upper weighs in at.

    Or does anyone make a ultra-lightweight alloy upper? or how about a scandium steel barrel in pencil profile?

    • JumpIf NotZero

      Scandium is merely an additive to aluminum. Usually defined as an 8xxx series.

      To the best of my knowledge there is no such thing as scandium steel.

      Lightweight barrels get no lighter than pencil steel barrels, but some companies are aggressively fluting their thicker profile steel to come close in weight, lotharwalther has some aluminum sleeve method they claim gives pencil barrels their stiffness back, and companies like ProofResearch use carbon weave on top of thin steel to do the same. The last I can confirm works well.

      • noob

        Ah thanks. I was confused about the S&W scandium revolvers. So the cylinder in those is steel or Ti, but the frame of the S&W revolver is Al-Sc alloy.

      • dragon5126

        the sleeved barrels don’t save any weight by the time they are all said and done. A standard contour barrel weighs the same as the sleeved which give the rigidity of a bull barrel without the weight. However, these barrels have yet to prove they stand up to the test of time. While they are fine on blowback and bolt/manual action firearms. they are yet to prove themselves time wise on gas operated weapons like the AR. You can fire as many rounds as you want, in a short period of time, and claim it will hold up to say X thousands of rounds. But spaced over time the hot gasses and time work differently to oxidize the sleeve composition and how it comes together at the gas port…

    • dragon5126

      remember cut that barrel profile too thin and it will whip and string as it heats, that was the issue with the older Mini 14’s cut the upper to light and it will wear out excessively fast even the Carbon 15’s aren’t noted for long lives or relative strength… theoretically they could sleeve a barrel but it would not gut much weight from the setup since the sleeve would need to be a minimum thickness for strength and the steel barrel could be thinner… and you are talking about 14.5 inches with a permanent muzzle brake attached. So the weight savings would be best placed in the fore-end.

  • Thomas Gomez

    Tensile strength of magnesium?

    • Tensile properties

      F temper:
      Tensile strength: 220 MPa (32 ksi)
      Yield strength: 130 MPa (19 ksi)
      Elongation: 6% in 50 mm (2 in.)

      Compressive yield strength

      F temper: 130 MPa (19ksi)

      Poisson’s ratio


      Elastic modulus

      Tension, 45 GPa (6.5 x 106 psi)

      • Ian

        Since that’s not the “secret” alloy above, all those specifications are moot. Because if those were the Yield and Ultimate strengths, that would make it worse than half as strong as 7075.

        • dragon5126

          he DID ask for the tensile strength of Magnesium, and not the alloy which is a hard witch… I had to stone out the trigger cut on one of mine. and I literally had to STONE it… it tore up the micro diamond file I tried first. And before anyone asks without reading my comment on it I have two built, a rifle and a pistol and I WILL buy more. I do like them over straight aluminum, I am not fond of the thin finish however, but on pieces I intend to do custom finishes on, big deal. I’ve been working on ARs since 78… don’t remember when I first started building them. been doing custom work since 78 as I said… Ive seen a lot of whining and complaining about what wont work, only to see it work… I will tell you one thing. there is no secret alloy. if there was this lower would have patents stamped all over it And it would have the name of some metallurgy firm emblazoned on it that’s the way the business world works. MTS simply went to a company that does magnesium alloys and said here are the designs, here is our money. Make it.

  • Patrick

    Finally, someone reinforces the front pivot. Now if only those polymer lowers would do the same.

  • Blaine

    I’d like to politely point out that the lower says MAG Tactical Systems, not Mag Tech. Mag Tech is a Brazilian ammunition company, and I don’t know that they produce any firearms.

  • 306_AD

    Kind of a solution to a problem that never existed. Most of the weight balance issue attributed to modular rifles is due to the upper and barrel. Weight of the lower was never really an issue since it’s so close to the grip. Nice product though.

    • dragon5126

      have to disagree heavily. it has nothing to do with how close it is to the grip it has to do with over all weight, balance of the weight and what accessories you put on it. for example close to half the weight of your upper can be right over the lower putting the majority of the weight on your strong arm adversely affecting the balance and as such your trigger control. Add a proper riser mount and optics and you have more weight suddenly its out of balance. all the weight is now on your wrist, stressing the flexor tendon before you even touch the trigger.

  • dragon5126

    I have two and while they are ice and tight, the finish, in a word, sucks. it is nowhere what I would call durable. simple assembly has left multiple scratches. out came the alumahide touch up marker, doesn’t quite match but wtf they are for hunting and will eventually be ceracoated … but they DO make a difference in the balance of the firearm were these on varmint rifles with long heavier barrels, I would not like. one is on an 8 inch pistol and works fine the other a 16 inch carbine… not bad.

    • bobby

      With your builds, did you have a hard time rotating the safety selector? A side note….my MAG lower came with paperwork saying that it wasn’t coated, just painted at the factory and suggested duracoating or cerakoting

      • dragon5126

        the only place I had an issue was on one the fcg was too tight. the other no problem. I don’t recall which coating they use, but it IS coated not anodized, per a review in one of the industry magazines that was posted online a while back. I believe it is duracoat, but not 100% positive. I still haven’t gotten around to coating mine, but then again I haven’t finished the mods and additions yet when I do, I intend to do everything in a mat pattern

  • Jon

    Can someone tell me if the Mag Tactical lower receiver is mil-spec or commercial?